Example embodiments relate generally to semiconductor devices, and more particularly to a line memory device and an image sensor including the line memory device.
Portable devices such as a digital camera, a camera phone, etc. include an image sensor configured to capture an image and particularly a complementary metal-oxide semiconductor (CMOS) image sensor (CIS) is widely used in the portable devices. The CIS generally includes a line buffer memory to increase a data processing speed. Outputs of an analog-to-digital converter (ADC) may be stored in the line buffer memory and the line buffer memory may output the stored data while the ADC performs a conversion process for the next data.
A plurality of memory cells in the line buffer memory are commonly coupled to a data line pair at different nodes, and data bits from the memory cells are sequentially or serially transferred to a sense amplifier through the common data line pair. In this case, the data bits are transferred to the sense amplifier with different delay times, because transfer distances from the respective memory cells to the sense amplifier are different from each other. The different delay times limit the frequency, that is, the cyclic period of a read clock signal of the line buffer memory, thereby degrading overall performance of the CIS including the line buffer memory.